This invention is directed to an improvement in a wheelchair wherein the wheelchair can be powered by the occupant therein by the occupant pushing a lever away from the occupant. Movement of the lever transfers power to the appropriate driving wheel of the wheelchair to propel the wheelchair. When the lever is in a neutral position, however, the wheelchair is capable of being moved by more conventional methods such as using the push rims normally attached to the wheels of the wheelchair, or by pushing by an assisting person in the normal manner.
Many wheelchairs augmented with devices wherein the occupant of the wheelchair can propel himself have been developed. Typical of such wheelchairs are those in U.S. Pat. Nos. 3,994,509; 3,309,110; 3,877,725; 3,666,292 and 4,274,651. In the U.S. Pat. No. 3,994,509 an extensive discussion is directed to certain of the negative aspects of many of the prior known wheelchairs which have been augmented with devices for self-propulsion. Others of the patents listed in this paragraph also have such discussions.
One thing which can be gleaned by reviewing the patents which have issued in this art area is that there is a lot of disagreement as to what is advantageous and what is disadvantageous in devices of this type. Certain inventors have deemed it disadvantageous to only get power from one of a forward or reverse stroke of devices utilizing levers capable of being pushed back and forth. To this end, U.S. Pat. Nos. 3,994,509 and 3,666,292 have developed systems wherein the power of both the forward and reverse stroke is utilized. U.S. Pat. No. 4,274,651 skirts the problem entirely by sustituting rotating cranks instead of levers which can be moved back and forward.
U.S. Pat. No. 3,309,110 develops its power stroke in returning the lever back toward the occupant of the chair and teaches the use of a "Y" shaped apparatus which enables the lever to be gripped with something other than a fist, such as positioning the wrist within the "Y" shaped apparatus.
U.S. Pat. No. 3,877,725 teaches utilizing the forward motion of the lever as the power stroke in a normal instance, and the adaptation of the mechanism such that, to go backwards, a rearward stroke of the lever can be utilized.
While all of the above noted patents certainly have their individual, unique advantages, it is deemed that all of them also suffer with certain defects.
As U.S. Pat. No. 3,309,110 notes, many of the persons confined to wheelchairs and the like do not have use of their fists sufficiently such that they can grip a lever or a crank and hold on to the same while pushing or rotating. This patent, as noted above, attempted to solve this problem by utilizing a "Y" shaped member which can be cocked around the wrist. If a person confined to a wheelchair suffers from arthritis or the like, deformities of the hands and wrists are quite frequent. Because of the pain associated with the joint, even the use of the "Y" shaped member of U.S. Pat. No. 3,309,110 could be precluded. Further, any wheelchair having propulsion levers, cranks, or the like, which require the pulling of the lever back toward the occupant during all of or a portion of the power stroke, continually direct a force on to the occupant, sliding the occupant forward on the seat in response to the pulling of the lever backward by the occupant. While this does not constitute a problem in those individuals who are fairly heavy, in the handicapped person who carries little body weight, the constant tugging of this perkson's lighter body forward, in attempts to pull back on the lever in a power stroke, can lead to failure of acceptance of use of the device by such a person.
It could then be summed up that, with regard to the direction of stroke of a lever, crank or the like, because of gripping problems and because of body weight problems, it is considered advantageous to utilize as a power stroke a movement away from the body of the occupant of the chair. Because of this factor, many of the known prior devices in this art area are thus excluded.
Additionally, many of the wheelchairs equipped with self-propelling devices do not allow for disattachment of these devices from the driving wheels or, if the devices can be disattached from the driving wheels, detachment is inconvenient and sometimes impractical. U.S. Pat. No. 3,994,509 provides a simple push button for detaching the interconnection between its driving levers and the driving wheels. Unfortunately, if a hand is occupied in depressing the push button, that same hand cannot be utilized to move the wheels in the more conventional manner by pushing on the push rims normally attached to the side of the wheels of the wheelchair. U.S. Pat. No. 3,666,292 provides no means for disattaching levers, such that whenever the wheelchair is moving, the levers are continually oscillating back and forth, which can serve as a hazard. Many times, the occupant of the wheelchair wishes to utilize the push rims on the individual wheels for moving short distances, turning in circles or, at other times, the occupant of the wheelchair simply lets another person push him around utilizing the gripping means normally found on the upper back of the wheelchair.
In those instances when the occupant of the wheelchair wishes either someone else to push him, or wishes to push himself, or move himself via the push rims on the wheels, placement of any levers or the like which continually oscillate, such as those in U.S. Pat. No. 3,666,292, or which are in the way of use of the push rims such as those seen in U.S. Pat. No. 3,309,110, is considered disadvantageous.
In view of all of the problems discussed above, it is considered that while many approaches have been taken toward providing a wheelchair which is conveniently used by the occupant therein to propel himself, each of the known devices suffer from one or several defects which has prevented wide acceptance and use of these type of devices.